______the damage is done, it will take many y...

______the damage is done, it will take many years for the farmland to recover.

A.Until

B.Unless

C.Once

D.Although

高三英语单项填空中等难度题查看答案及解析

_____the damage is done, it will take many years for the farmland to recover.

A. Until　 　　　　　　　　 B. Unless

C. Once　 　　　　　　　　　 D. Although

高三英语单项填空中等难度题查看答案及解析

_____the damage is done, it will take many years for the farmland to recover.

A. Until　　 　　　　　　 　 B. Unless

C. Once　　 　　　　　　　 　　 D. Although

高三英语单项填空中等难度题查看答案及解析

_________ environmental damage is done, it takes many years for the ecosystem to recover.

A. Even if　　　　 B. If only　　　　 C. While　　　 D. Once

高三英语单项填空中等难度题查看答案及解析

______ environmental damage is done，it takes many years for the ecosystem to recover．

A．Even if　 B．If only

C．As if　 　 D．Once

高三英语单项填空简单题查看答案及解析

______ environmental damage is done，it takes many years for the ecosystem to recover．

A． Even if　　　　　　　　　　 B． If only

C． As if　　　　　　　　　　　　 D． Once

高三英语单项填空简单题查看答案及解析

Many jobs must be done with two people. One person takes the lead. The other helps. So it is with the human body. Much of our body depends on the cooperation between substances. When they work together, chemical reactions take place smoothly. Body systems are kept in balance.

Some of the most important helpers in the job of good health are the substances we call vitamins. The word “vitamin” dates back to Polish scientist Casimir Funk in 1912. He was studying a substance in rice. Funk believed the substance belonged to a group of chemicals known as amines (胺类). He added the Latin word “vita”, meaning life. So he called the substance a “vitamine”—an amine necessary for life.

Other studies found that not all vitamins were amines. So the name was shortened to vitamin. But Funk was correct in recognizing their importance.

Scientists have discovered 14 kinds of vitamins. They say vitamins help to carry out chemicals changes within cells. If we do not get enough of the vitamins, we are at risk of developing a number of diseases. This brings us back to James Lind of Scotland. In the 1740s, Lind was a doctor for the British Navy. He was investigating a problem that had existed in the Navy for many years.

The problem was the disease scurvy(坏血病). The sailors were weak from bleeding inside their bodies. Even the smallest wound would not heal. Doctor Lind thought the sailors were getting sick because they failed to eat some kinds of foods when they were at sea for many months.

Doctor Lind separated twelve sailors who had scurvy into two groups. He gave each group different foods to eat. One group got oranges and lemons. The other did not. The men who ate the fruit began to improve within seven days. The other men got weaker.

However, which foods should be eaten to keep us healthy? Let us look at some important vitamins for these answers.

1.Why was the name “vitamine” shortened to “vitamin”?

A. Because Funk was totally wrong.

B.Because few vitamins were amines.

C. Because there were new findings.

D. Because the latter was easy to remember.

2.The underlined word “This” in the fourth paragraph probably refers to that _______.

A. people tend to develop many diseases

B. lack of the vitamins causes disease

C. vitamins help chemical changes within cells

D. it is common for people to get no enough vitamins

3.Doctor Lind proved eating fruits can prevent scurvy by means of _______.

A. comparing　　 B. analyzing　　 C. surveying　　 D. questioning

4.What is the main topic of the passage?

A. Food to keep us healthy.

B. The benefits of vitamins.

C. Research into scurvy.

D. Facts about vitamins.

高三英语阅读理解中等难度题查看答案及解析

Your Car Is Ready for Take-off

The flying car has been talked about for many years，but now it appears that the idea is about to become a reality.

An international company has built a two-seater plane that, at the touch of a button ，transforms into a car perfectly suitable for driving on public roads. It has been designed so that the wings fold up automatically； and it takes just 15 seconds to switch between flying and driving. With its wings fully open and the propeller(螺旋桨）spinning, it can take off from any airfield.

Flying cars are quicker than traditional ones for travelling from city to city，and they can run on ordinary fuel. Another big advantage is that they are cool ，like something you would see in an action film. At the moment ₉ however, the flying car’s wheels are illegal to leave the ground. That is not because of technical reasons or problems with the design. It is because the various road and aircraft authorities simply cannot agree on whether it is a car or a plane.

“The government and the authorities have never thought seriously about a flying car, says Alan Price ，the president of the company that has developed it. “I wanted a car that could fly and drive ，but it is difficult to find an organization prepared to insure the vehicle against accidents.

Nevertheless _? the company hopes to produce and deliver its first flying car soon. The company already has orders for 40 of them. The majority the potential customers are older and some are retired。There have even been orders from some people who have no pilot's license.

The flying car will cost around $ 200_.000. “For an airplane _， that^’s a very reasonable price， but for a car, It's quite expensive，” explains Alan. “But it just is not possible to make a $ 10，000 flying car yet. ”

This latest means of transport will not become a mass-market item in the near future，but in the long term it has the potential to change the way you travel. It will become no more expensive than driving your car on the motorway. Travel time could be reduced by more than half.

So the next time you are told to fasten your seat belt, it may be to prepare for take-off.

1.We know from the passage that the flying car______

A．has to run on special fuel                 B．will replace traditional planes

C．is popular with the rich                   D．can shift between two forms

2.The flying car is presently forbidden to take off because______.

A．many people think driving it not very safe

B．it’s hard to decide whether it's a car or a plane

C．the government and the authorities don’t accept it

D．there are still some technical problems to be solved

3.We can learn from the passage that______.

A．few people will be able to afford a flying car

B．flying cars may share the market in the future

C．traffic jams will disappear because of flying cars

D．driving a flying car doesn’t require a pilot’s license

高三英语阅读理解中等难度题查看答案及解析

It will be many years ______the doctors and medical scientists can find _____ for cancer.

高三英语单项填空中等难度题查看答案及解析

_________ it takes many years to gain the skills of an expert.

A. It is well known to us that     B. As is known to us that

C. As we know that             D. That is well known to us

高三英语单项填空简单题查看答案及解析